GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

    Important: The vehicle communication unit (VCU) has a specific set of unique numbers that tie the module to each vehicle. These numbers, the 10-digit station identification and the 11-digit electronic serial number, are used by the National Cellular Network and OnStar® to identify the specific vehicle. Because these numbers are tied to the vehicle identification number of the vehicle, you must never exchange these parts with those of another vehicle.

  1. Remove the instrument panel (I/P) trim panel. Refer to Instrument Panel Upper Trim Panel Replacement .
  2. Remove the I/P cluster harness in order to gain access to the VCU bracket screw.

  3. Object Number: 661523  Size: SH
  4. Remove the screw securing the VCU to the bracket.
  5. Disconnect the electrical connectors.
  6. Remove the VCU from the bracket.
  7. The old VCU must be returned for core credit.

Installation Procedure

  1. Record the 11-digit ESN from the label on the new VCU module.

  2. Object Number: 661523  Size: SH

    Notice: In order to avoid damage to the circuit board, do NOT over-tighten the thumb screws. Using your fingers, apply only a light pressure.

  3. Install the VCU to the bracket.
  4. Connect the electrical connectors to the VCU.
  5. Notice: Refer to Fastener Notice in the Preface section.

  6. Install the screw.
  7. Tighten
    Tighten the screw to 9 N·m (80 lb in).

  8. Install the I/P cluster harness.
  9. Install the I/P trim panel. Refer to Instrument Panel Upper Trim Panel Replacement .
  10. Important: After replacing the VCU, you must reconfigure the OnStar® system. Failure to reconfigure the system will result in an additional customer visit for repair.

  11. Reconfigure the OnStar® system. Refer to OnStar Reconfiguration .
  12. Return the old VCU for core credit.